TWI748007B - Method for lithography patterning - Google Patents

Abstract

The present disclosure provides an embodiment of a method for lithography patterning. The method includes coating a photoresist layer over a substrate, wherein the photoresist layer includes a first polymer, and a first photo-acid generator (PAG), and a chemical additive mixed in a solvent; performing an exposing process to the photoresist layer; and performing a developing process to the photoresist layer to form a patterned photoresist layer. The chemical additive has a non-uniform distribution in the photoresist layer.

Description

Lithographic patterning method

The embodiment of the present invention relates to the manufacturing method of the semiconductor device, and more particularly to the composition of the photosensitive film in the photolithography and the method of using it.

The semiconductor integrated circuit industry has experienced exponential growth. The technological progress of integrated circuit materials and design has enabled each generation of integrated circuits to have smaller and more complex circuits than the previous generation. In the evolution of integrated circuits, the functional density (the number of interconnection devices per chip area) generally increases as the geometric size (such as the smallest component or circuit) decreases. The size reduction process is usually beneficial to increase production capacity and reduce related costs. The aforementioned reduction in size also increases the complexity of the manufacturing process of the integrated circuit. For example, the existing photolithography process includes applying a photoresist to a substrate, and exposing the photoresist with electromagnetic waves passing through the photomask. The photoresist absorbs electromagnetic waves and generates acid, which can deprotect the leaving group and dissolve the photoresist in the developer. Since the photoresist absorbs electromagnetic waves, the intensity of the electromagnetic waves at the bottom of the photoresist is lower than the intensity of the electromagnetic waves at the top of the photoresist. In this way, the deprotection reaction at the bottom of the photoresist is less, that is, the dissolution rate at the bottom is lower. This mechanism will cause footing contours, especially in the small hole and small groove pattern, because the electromagnetic wave intensity is lower in the small-sized pattern mentioned above. Footprint outlines will cause the patterned photoresist to have inconsistent key dimensions, such as the key dimensions detected after etching. When the pattern of the photoresist is transferred to the material layer below, the photoresist in the footing area serves as an etching mask and makes the patterned material layer have inconsistent critical dimensions. Increasing the solubility of the photoresist can improve the problems associated with the footing profile, but this will result in a rounded top profile, reduced photoresist thickness, and deterioration of critical dimension consistency. Currently, photoresist and methods using photoresist are urgently needed to solve the above-mentioned problems.

An embodiment of the present invention provides a method for lithography patterning, including: coating a photoresist layer on a substrate, wherein the photoresist layer includes a first polymer, a first photoacid generator, and a chemical additive mixed in a solvent, Among them, the distribution of chemical additives in the photoresist layer is inconsistent; an exposure process is performed on the photoresist layer; and a development process is performed on the photoresist layer to form a patterned photoresist layer.

10‧‧‧Photoresist

10’‧‧‧patterned photoresist

10a‧‧‧Exposed part

10b‧‧‧Unexposed part

12‧‧‧Polymer

14‧‧‧Photo acid generator

16‧‧‧Acid active base

18‧‧‧Photosensitizer

20‧‧‧Quenching Agent

22‧‧‧Solvent

24‧‧‧Chemical additives

28A, 28B, 28C, 28D‧‧‧Chemical structure

30‧‧‧Dissolving additives

32‧‧‧The first structural unit

34‧‧‧Second structural unit

40‧‧‧Photoacid generator additive

42, 44, 52, 54‧‧‧Chemical Unit

46‧‧‧Photosensitive unit

50‧‧‧Quenching agent additives

56‧‧‧Quenching Unit

48、58‧‧‧Strong Polarity Unit

60‧‧‧First polymer additive

70‧‧‧Second polymer additive

72‧‧‧First functional unit

74‧‧‧Second functional unit

100‧‧‧Method

102, 104, 106, 108, 110‧‧‧ steps

200‧‧‧Semiconductor structure

202‧‧‧Substrate

204‧‧‧Lower Floor

204’‧‧‧Patternized hard mask

Figure 1A is a block diagram of a photoresist in some embodiments of the present invention.

FIG. 1B is a cross-sectional view of the photoresist coated on the substrate in some embodiments.

Figures 2, 3, 4, 5, 6, and 7 show the chemical structures of the chemical additives in the photoresist in some embodiments.

Figure 8 is a flow chart of the lithographic patterning method in some embodiments.

Figures 9A, 9B, 9C, 9D, and 9E are cross-sectional views of the semiconductor structure in various manufacturing stages in some embodiments.

The different embodiments or examples provided in the following content can implement different structures of the present invention. The embodiments of specific components and arrangements are used to simplify the present invention but not to limit the present invention. For example, the description of forming the first member on the second member includes direct contact between the two, or there are other additional members between the two instead of direct contact. In addition, labels and/or symbols may be repeated in various examples of the present invention, but these repetitions are only used for simplification and clear description, and do not mean that units with the same labels and/or symbols between different embodiments and/or arrangements have The same correspondence.

In addition, spatially relative terms such as "below", "below", "lower", "above", "above", or similar terms can be used to simplify the description of an element and another element in the icon Relative relationship. Spatial relative terms can be extended to elements used in other directions, not limited to the directions shown in the figure. The components can also be rotated by 90° or other angles, so directional terms are only used to describe the directions in the illustration.

The present invention relates to a manufacturing method of a semiconductor device, and more particularly to the composition of a photosensitive film in lithography and a method of using it. After exposing the photoresist film with radiation such as ultraviolet, deep ultraviolet, or extreme ultraviolet (or other radiation such as electron beam) in the photolithography patterning, the photoresist is developed with a developer (chemical solution). The developer can remove part of the photoresist film (such as the exposed part of the positive photoresist or the unexposed part of the negative photoresist) to form a photoresist pattern. The photoresist pattern may include a line pattern and/or a groove pattern. In the subsequent etching process, the photoresist pattern can be used as an etching mask to transfer the pattern to the underlying material layer. In other embodiments, an ion implantation process can then be performed on the underlying material layer, such as a semiconductor layer, which can use a photoresist pattern as an ion implantation mask.

A photoresist that uses a chemical amplification mechanism is generally called a chemically amplified photoresist. FIG. 1A is a block diagram of the photoresist 10 in some embodiments. When the photoresist 10 is coated on a workpiece such as a semiconductor substrate, the photoresist 10 includes a variety of chemical compositions mixed in a solution. The composition of the photoresist 10 of various embodiments will be described in detail below.

The photoresist 10 includes a polymer 12 to resist etching or ion implantation in the semiconductor manufacturing process. In various embodiments, the polymer 12 includes polynorbornene-co-maleic anhydride, polyhydroxystyrene, or acrylate-based polymers. For example, acrylate-based polymers include polymethyl methacrylate. In addition, polyhydroxystyrene is also sensitive to extreme ultraviolet rays and can be used as a photosensitizer for extreme ultraviolet light resists. The polymer 12 also includes multiple side positions, which can be chemically bonded to other chemical groups.

The photoresist 10 includes an acid-generating compound, such as a photoacid generator 14. The photoacid generator 14 absorbs energy and generates acid. In some embodiments, the photoacid generator 14 includes a benzene ring. In a specific example, the photoacid generator 14 contains a cation, such as a triphenyl enamel group, and an anion, such as a trifluoromethanesulfonic acid anion. In some examples, the cation contains a sulfonic acid group or a fluorinated alkylsulfonic acid group.

In some examples, the photoresist 10 further includes an acid active group or a dissolution inhibitor bonded to the main chain of the polymer. The acid active group 16 can produce a chemical change in response to the acid. For example, the acid active group 16 will be cut in the presence of acid, thus increasing or decreasing the photoresist polarity. Therefore, in the exposed area of the photoresist layer, the acid generator will deprotect the acid active group 16. The exposed photoresist changes polarity and solubility. For example, the solubility of the exposed photoresist material in the developer increases (for positive photoresist) or decreases (for negative photoresist). When the exposure dose of the lithographic exposure process reaches the critical dose, the exposed photoresist material will not dissolve in the developer (or dissolve in the developer). In one example, the acid active group 16 includes a third butoxycarbonyl group.

The photoresist 10 may further include a photosensitizer 18 to increase the sensitivity and efficiency of the photoresist material to light. The photoacid generator in the photoresist material may not be sensitive to extreme ultraviolet rays, but is more sensitive to electrons or other rays such as ultraviolet rays or deep ultraviolet rays. In this way, the sensitivity of the photoresist material with the photosensitizer 18 to the first rays is improved. In particular, the photosensitizer 18 is sensitive to the first radiation and can generate a second radiation in response to the first radiation. In this embodiment, the first rays are extreme ultraviolet rays, and the second rays are electrons. The photosensitizer 18 absorbs extreme ultraviolet rays and generates secondary electrons. In addition, the photoacid generator 14 is sensitive to second electrons and can absorb secondary electrons and generate acid. In various examples, the photosensitizer 18 includes a fluorine-containing chemical, a metal-containing chemical, a phenol-containing chemical, or a combination thereof. In some examples, the photosensitizer 18 includes polyhydroxystyrene, polyfluorinated styrene, or polychlorinated styrene. The photosensitizer 18 may be bonded to the polymer 12.

In some embodiments, the photoresist 10 may include other components such as quenchers, which are alkaline and can neutralize acids. The quenching agent can be substituted or matched with other components to inhibit the reaction of other active components of the photoresist (such as photoacid generator or photoacid). In one example, the quencher 20 contains a nitrogen atom whose unpaired electrons can neutralize the acid. Various chemical compositions are mixed in the solvent 22 to form a photoresist solution for coating on the workpiece. The solvent 22 may be an aqueous solvent or an organic solvent. The quencher 20 is distributed in the photoresist solution or is bonded to the polymer 12.

The photoresist 10 also includes a chemical additive 24 mixed with other components in the solvent 22. The chemical additive 24 is designed to change the photoresist and has a gradual distribution in the photoresist coated on the workpiece, so the imaging effect of the photoresist and the quality of the corresponding exposure process can be adjusted.

In the existing photoresist layer and related photolithography process, the photoresist layer can absorb the radiation from the photolithography process and generate acid. The acid cleaves the acid active group, resulting in a deprotection effect and making the exposed photoresist layer more soluble in the developer. Since the photoresist absorbs rays, the intensity of the rays in the bottom of the photoresist layer is less than the intensity of rays in the top. The deprotection effect and dissolution rate of the bottom of the photoresist layer are lower than that of the top of the photoresist layer. The above phenomenon will cause the contour of the footing, especially in the pattern of small holes/grooves, thereby inducing inconsistent critical dimensions (or inconsistent critical dimensions).

Adding chemical additives 24 to the photoresist allows the chemical additives 24 in the photoresist 10 coated on the workpiece to have a gradual distribution to compensate for the aforementioned top-to-bottom process variation, thereby improving the resolution and pattern of photolithography imaging Quality.

The gradual distribution or gradual concentration of chemical additives will be further described in conjunction with the cross-sectional view of the photoresist 10 coated on the substrate in Figure 1B. The concentration of the chemical additive 24 from the upper surface to the lower surface is not a fixed value. In one example, the concentration of the chemical additive decreases from the upper surface to the lower surface, as shown in the exemplary curve 25. In the figure, the vertical axis Z refers to the distance from the lower surface, and the horizontal axis refers to the concentration of chemical additives in the photoresist layer 10. In another example, the chemical additive concentration increases from the upper surface to the lower surface, as shown by the exemplary curve 26. For the curve 26, the concentration of the chemical additive in the top of the photoresist layer 10 is less than the concentration of the chemical additive in the bottom of the photoresist layer 10. The top and bottom are the parts above and below the reference center line respectively. In this example, the top concentration is the average concentration at the top, and the bottom concentration is the average concentration at the bottom.

Various embodiments of the chemical additives 24 will be further detailed as follows.

In one embodiment, the chemical additive 24 in the photoresist 10 is a dissolving additive. The chemical structure of the dissolving additive is designed to have low surface tension and dissolution inhibition. In particular, the chemical structure of the dissolved additive has two functional units bonded together. In some examples, the first functional unit is a hydrophobic unit such as an alkyl group, a cycloalkyl group, or an adamantyl group. In some other examples, the first functional unit may include one of the chemical structures 28A, 28B, 28C, and 28D shown in FIG. 2. The first functional unit can reduce the solubility of the photoresist in the developer. In some examples, the second functional unit is a fluorochemical, such as a fluoropolymer. The surface tension of the second functional unit is lower than some values (such as 20mN/m in this example), so the dissolved additives float and have a gradual distribution in the coated photoresist layer, especially decreasing from the top of the photoresist layer to the bottom The concentration (gradual distribution). An example of the dissolving additive 30 has the chemical structure shown in FIG. 3, which is a copolymer in which the first structural unit 32 and the second structural unit 34 are bonded together. The first structural unit 32 and the second structural unit 34 each have a first function and a second function, corresponding to the first functional unit and the second functional unit. In particular, the function of the first structural unit 32 is to suppress the dissolution rate of the photoresist in the developer, and the function of the second structural unit 34 is to achieve a gradual distribution. X and Y are suitable integers. The dissolving additive 30 is designed to have appropriate X and Y to meet the standards required for better photoresist imaging quality. For example, the molecular weight of the dissolved additive is greater than 4000, and further greater than the molecular weight of polymer 12. In this way, the dissolved additives have a gradual distribution, especially from a higher concentration on the upper surface of the photoresist to a lower concentration on the lower surface of the photoresist.

The photoresist has a gradual distribution of dissolving additives therein, and the dissolution rate of the bottom of the photoresist layer is higher, and the dissolution rate of the top of the photoresist layer is lower. In this way, the contour of the footing can be reduced and the consistency of key dimensions can be improved.

In another embodiment, the chemical additive 24 in the photoresist 10 is a photoacid generator additive (also referred to as a second photoacid generator). The photoacid generator additive is another photoacid generator, which has a different chemical structure from the photoacid generator 14. The photoacid generator additive is designed as a photoacid generator, and has strong polar units to achieve the gradual distribution in the photoresist 10. In particular, the chemical structure of the photoacid generator additive has two functional monomers bonded together. The first functional unit is a photon sensitive unit, which can generate acid during the photolithography process. The second functional unit is a strong polar unit, which can interact with the intermediate layer. This mechanism will be explained as follows. In some examples, the chemical structure comparison between the photoacid generator 14 and the photoacid generator additive 40 is shown in FIG. 4. The photoacid generator 14 includes two chemical units 42 and 44, and the photoacid generator additive 40 includes a photosensitive unit 46 and a strong polar unit 48. Due to the force between the strong polar unit 48 of the photoacid generator additive 40 and the intermediate layer, the bottom concentration of the photoacid generator additive 40 in the photoresist layer is higher than the top concentration. In particular, the photoacid generator additive 40 has a gradual distribution in the photoresist layer, so the corresponding photoacid generator additive concentration increases from the top to the bottom of the photoresist layer. The photoacid generator 14 has a substantially uniform distribution in the photoresist layer. After the photoacid generator 14 is combined with the photoacid generator additive, the bottom concentration of the photoacid generator in the photoresist is higher than the top concentration, so it can compensate for the lower deprotection effect, reduce the footing profile, and improve the consistency of key dimensions sex.

Similarly, the chemical additive in the photoresist 10 may be a quencher additive (also referred to as a second quencher). The quenching agent additive is another quenching agent, which has a different chemical structure from the quenching agent 20. The quenching agent additive is designed as a quenching agent, and has a strong polar unit to achieve the gradual distribution in the photoresist 10. In particular, the chemical structure of the quenching agent additive has two functional units joined together. The first functional unit is designed to have the function of quenching agent. The second functional unit is a strong polar unit, which can interact with the intermediate layer. In some examples, the second functional unit is composed of a fluorine-rich polymer, which allows the second quenching agent to have a gradually increasing concentration from the lower surface of the photoresist toward the upper surface. In some examples, the chemical structure comparison between the quencher 20 and the quencher additive 50 is shown in FIG. 5. The quenching agent 20 includes two chemical units 52 and 54, and the quenching agent additive 50 includes a quenching unit 56 and a strong polar unit 58. Due to the force between the strong polar unit 58 of the quencher additive 50 and the intermediate layer, the top concentration of the quencher additive 50 in the photoresist 10 is higher than the bottom concentration. In particular, the quencher additive 50 has a gradual concentration in the photoresist layer, so the corresponding quencher additive concentration decreases from the top to the bottom of the photoresist layer. The quenching agent 20 has a substantially uniform distribution in the photoresist layer. The total concentration of the quenching agent 20 and the quenching agent additive is higher in the top part of the photoresist layer than in the bottom part of the photoresist layer. The above-mentioned concentration distribution can compensate for the lower deprotection effect, reduce the contour of the footing, and improve the consistency of key dimensions.

In another embodiment, the chemical additive 24 in the photoresist 10 is a first polymer additive (or referred to as a second polymer). The first polymer additive can resist etching like the polymer 12, but the solubility of the first polymer additive in the developer is different, and the spatial distribution of the first polymer additive in the photoresist is different. In particular, the chemical composition of the first polymer additive is designed to have an inconsistent distribution in the photoresist layer. The polymer 12 and the first polymer additive have inconsistent solubility in the developer, for example, the solubility at the top of the photoresist layer is lower than the solubility at the bottom of the photoresist layer. In this embodiment, the polymer 12 and the first polymer additive are designed to have different chemical structures to achieve phase separation, so one (such as the first polymer additive) is substantially distributed on the top of the photoresist layer, and the other One (such as polymer 12) is substantially distributed in the bottom of the photoresist layer. In many examples, the activation energy of acid active groups, or the molecular weight, polarity, and ratio of polyhydroxystyrene, acid active groups with large steric obstacles, or lactones with large steric obstacles, can be used to adjust the polymer Solubility and distribution.

In this embodiment, the concentration of the first polymer additive 60 decreases from the top to the bottom of the photoresist layer, and can be adjusted to a gradual concentration. In addition, the concentration of the polymer 12 increases from the top to the bottom of the photoresist layer, and can be adjusted to an inconsistent concentration distribution. Figure 6 shows an exemplary structure of the polymer 12 and the first polymer additive 60 in some embodiments. In Figure 6, n1 and n2 are integers, and they are related to the degree of polymerization and molecular weight of the polymer 12 and the first polymer additive 60, respectively. In particular, the molecular weight of the first polymer additive 60 is greater than the molecular weight of the polymer 12, which can effectively reduce the top solubility of the photoresist to avoid loss of the photoresist and eliminate footing contours. In some examples, the molecular weight of the first polymer additive 60 is between 6,000 and 20,000, and the molecular weight of the polymer 12 is between 2,000 and 8,000. The first polymer additive 60 includes fluorine-containing units. In contrast, the polymer 12 is substantially distributed on the bottom of the photoresist layer, and the first polymer additive 60 is substantially distributed on the top of the photoresist layer. X, Y, and Z are suitable integers. The X, Y, and Z values of the first polymer additive 60 and the polymer 12 are designed to be in suitable ranges to meet the above-mentioned standards required for better photoresist imaging quality. For example, since Z is present (greater than or equal to 1), the molecular weight of the first polymer additive 60 is greater than the molecular weight of the polymer 12. In this example, Z is between 3 and 20.

In various examples, the first polymer additive is designed to be substantially distributed on the top of the photoresist layer. The first polymer additive has higher activation energy, higher molecular weight, fluorine, or a combination of the above than polymer 12 because of its lower solubility in the developer.

In another embodiment, the chemical additive 24 in the photoresist 10 is of a chemical composition, which, like the polymer 12, can provide the etching resistance required by the photoresist, but is higher than that provided by the polymer 12. It can be referred to as a second polymer additive. The second polymer additive and the polymer 12 have different etching resistance and spatial distribution. The second polymer additive is designed to have stronger etching resistance and has an inconsistent spatial distribution in the photoresist. In particular, the chemical composition of the second polymer additive is designed to have a gradual distribution in the photoresist layer, so the concentration of the second polymer additive at the top of the photoresist layer is substantially greater than its concentration at the bottom of the photoresist layer. In other words, the gradual distribution of the second polymer additive decreases from the upper surface of the photoresist layer to the lower surface of the photoresist layer. Similarly, the second polymer additive contains chemical units such as fluorine-containing units to achieve a gradual distribution in the photoresist layer.

Figure 7 shows an exemplary structure of the second polymer additive 70 in some embodiments. In Figure 7, n is an integer and is related to the degree of polymerization of the second polymer additive 70 and the molecular weight. In particular, the second polymer additive 70 has two chemical units bonded together. The first functional unit 72 contributes to greater etching resistance than the polymer 12. The second functional unit 74 contributes to the gradual distribution in the photoresist 10. In the example shown in FIG. 7, the second functional unit 74 contains fluorine. Due to the gradual distribution and greater etching resistance of the second polymer additive 70, the polymer 12 and the second polymer additive 70 together increase the etching resistance in the top and bottom. In this way, the second polymer additive 70 can improve the tolerance of the photoresist budget and have a larger tolerance of rounded contours. The second polymer additive 70 also improves critical dimension consistency. The lithography process using the above-mentioned photoresist material will be described in detail as follows.

FIG. 8 is a flowchart of a method 100 for patterning a substrate (such as a semiconductor wafer) in some embodiments of the present invention. By adopting advanced lithography processes such as deep ultraviolet lithography, extreme ultraviolet lithography, electron beam lithography, X-ray lithography, and/or other lithography systems to implement all or part of the method 100, the pattern can be improved The accuracy of the size. In this embodiment, extreme ultraviolet and/or electron beam lithography are the main examples. Additional steps may be performed before, during, or after the method 100, and additional embodiments of the method may replace, omit, or exchange some of the steps.

9A to 9E are cross-sectional views of the semiconductor structure 200 in various process stages in some embodiments. The method 100 will be described in conjunction with FIGS. 8 and 9A to 9E as follows, wherein the embodiment of the method 100 is used to fabricate the semiconductor structure 200. The semiconductor structure 200 can be an intermediate workpiece or a part thereof when an integrated circuit is made, and the integrated circuit can include logic circuits, memory structures, passive components (such as resistors, capacitors, or inductors), or active components (such as diodes). , Field Effect Transistor, Metal Oxide Half Field Effect Transistor, Complementary Metal Oxide Semi Transistor, Bipolar Transistor, High Voltage Transistor, High Frequency Transistor, Fin-shaped Field Effect Transistor, Other Three-dimensional Transistor, Gold Oxygen semi-transistor, complementary metal oxide semi-transistor, bipolar transistor, high-voltage transistor, high-frequency transistor, other memory cells), or a combination of the above.

As shown in FIGS. 8 and 9A, step 102 of the method 100 starts with the semiconductor structure 200. As shown in FIG. 9A, the semiconductor structure 200 includes a substrate 202. In one embodiment, the substrate 202 is a semiconductor substrate such as a wafer. In another embodiment, the substrate 202 includes silicon with a crystalline structure. In other embodiments, the substrate 202 includes other semiconductor elements such as germanium, semiconductor compounds such as silicon carbide, gallium arsenide, indium arsenide, or indium phosphide. The substrate 202 includes one or more layers of materials or compositions. The substrate 202 may include a silicon-on-insulation substrate, with stress/strain to improve performance, include one or more semiconductor devices or parts thereof, include conductive and/or non-conductive layers, and/or include other suitable structures and layers Things.

In this embodiment, a lower layer is formed on the substrate 204. The lower layer 204 may be a material layer that is subjected to a subsequent process such as patterning or implanting. For example, the lower layer 204 is a hard mask layer to be patterned. In another example, the lower layer 204 is an epitaxial semiconductor layer to be ion implanted. In one embodiment, the lower layer 204 is a hard mask layer, and the material contained therein may be silicon oxide, silicon nitride, silicon oxynitride, or other suitable materials or compositions. In one embodiment, the lower layer 204 is an anti-reflective coating such as a nitrogen-free anti-reflective coating, such as silicon oxide, silicon oxycarbide, or plasma-enhanced chemical vapor deposited silicon oxide. In various embodiments, the underlying layer 204 may include a high-k dielectric layer, a gate layer, an interface layer, a cap layer, a diffusion barrier layer, a dielectric layer, a conductive layer, other suitable layers, and/or the above combination.

In this embodiment, the lower layer may be a partial three-layer photoresist. In this example, the lower layer includes a base film and an intermediate film on the base film. In this embodiment, the bottom film is a carbon-rich polymer material, and the intermediate film is a silicon-rich material to provide etching selectivity. In some examples, both the base film and the intermediate film are formed by spin coating, and can be further cured by a curing step such as thermal baking or ultraviolet curing.

In some embodiments, the semiconductor structure 200 may be a photomask for patterning a semiconductor wafer. In this embodiment, the substrate 202 is a mask substrate, which may include a transparent material (such as quartz) or a low thermal expansion material (such as a silicon oxide-titanium oxide compound). The substrate 202 of the photomask may also include a material layer to be patterned. In this example, the substrate 202 of the photomask can be used to make a deep ultraviolet light barrier, an extreme ultraviolet photomask, or other types of photomasks. In summary, the lower layer 204 may be a material layer, which is patterned to define a circuit pattern. For example, the lower layer 204 is an absorption layer such as a chromium layer.

Step 104 of method 100 forms photoresist 10 on substrate 202 (see FIG. 9A). The photoresist 10 is sensitive to radiation used in the lithography exposure process and can resist etching. In an embodiment shown in FIG. 9A, the application method of the photoresist 10 is a spin coating process. In some embodiments, the photoresist 10 is further processed by a soft baking process. In some embodiments, the photoresist layer is sensitive to radiation, such as I-line light, deep ultraviolet (such as 248nm radiation of krypton fluoride excimer laser or 193nm radiation of argon fluoride excimer laser), extreme ultraviolet (such as 135nm)的光), electron beam, or ion beam.

In this example, the photoresist uses a chemically amplified photoresist material. For example, the chemically amplified photoresist material is a positive type, and its polymer material is soluble in the developer after reacting with an acid. In other embodiments, the chemically amplified photoresist material is a negative type, and its polymer is insoluble in a developer such as an alkali solution after reacting with an acid. In another example, the polymer material contained in the chemical square photoresist material changes its polarity after reacting with an acid.

Before and during the coating of the photoresist 10 on the substrate, the photoresist is in a liquid state. Therefore, the photoresist 10 can also be referred to as a photoresist solution. The photoresist 10 is as described in FIGS. 1A to 7. The photoresist 10 includes a polymer 12, a photoacid generator 14, a quenching agent 20, a solvent 22, and a chemical additive 24. The chemical additive 24 is designed to have a gradual distribution of chemical characteristics when it is coated on the substrate 202. In some examples, the chemical structure of the chemical additive 24 has two functional units bonded together: one functional unit can cause inconsistent distribution in the photoresist layer, and the characteristics of the other functional unit can be from top to bottom during the exposure process Compensate for the variation of the photoresist layer. The chemical additive 24 can be a dissolving additive (such as the dissolving additive 30 in Figure 3), a photoacid generator additive (such as the photoacid generator additive 40 in Figure 4), and a quenching agent additive (such as the dissolving additive 30 in Figure 5). The quencher additive 50), the first polymer additive (such as the first polymer additive 60 in Figure 6), or the second polymer additive (such as the second polymer additive 70 in Figure 7), such as The foregoing various embodiments.

As shown in FIGS. 8 and 9B, in step 106 of the method 100, in the lithography system, the photoresist 10 is exposed to a first radiation. In some embodiments, the first radiation is extreme ultraviolet (13.5 nm). In some embodiments, the first ray is I-line (365nm), deep ultraviolet such as krypton fluoride excimer laser (248nm) or argon fluoride excimer laser (193nm), extreme ultraviolet, X-ray, electron beam, Ion beam, and/or other suitable radiation. Step 106 can be performed in air, liquid (immersion lithography), or vacuum (extreme ultraviolet lithography or electron beam lithography). In some embodiments, the rays are directed to the photoresist, and the circuit pattern defined on the photomask is imaged on the photoresist. The photomask can be a transmissive or reflective photomask. The appropriate exposure mode can be either stepping or scanning. Various resolution enhancement techniques such as phase shifting, off-axis illumination, and/or optical proximity correction can be implemented through photomasks or exposure processes. For example, optical proximity correction can be integrated into the circuit pattern. In another example, the photomask is a phase shift photomask, such as an alternating phase shift photomask, an attenuated phase shift photomask, or a chromium-free phase shift photomask. In another example, the exposure process is performed in an off-axis irradiation mode. In some other embodiments, the radiation is directly adjusted in a predetermined pattern, such as an integrated circuit layout, without using a photomask. For example, a digital pattern generator or direct write mode can be used. In this embodiment, the rays are extreme ultraviolet rays and step 106 is performed in an extreme ultraviolet lithography system (such as the aforementioned extreme ultraviolet lithography system).

After the exposure process, step 106 may further include other steps such as heat treatment. In this embodiment, step 106 includes performing a post-exposure baking process on the semiconductor structure 200 (especially the photoresist 10 coated on the substrate 202). In the post-exposure baking process, the acid active groups 16 in the exposed part of the photoresist material are cut off, so that the exposed part of the photoresist material is chemically changed (for example, more hydrophilic or more hydrophobic). In certain embodiments, the post-exposure baking process can be performed in a thermal chamber between about 120°C and about 160°C.

After step 106, a latent pattern is formed on the photoresist 10. The latent pattern of the photoresist refers to the exposure pattern on the photoresist, which will eventually be transformed into a physical photoresist pattern after the development process. The latent pattern of the photoresist 10 includes an exposed portion 10a and an unexposed portion 10b. In the latent pattern of this example, the exposed portion 10a of the photoresist layer is chemically changed. In some cases, the exposed part of 10a can be deprotected and the polarity change can be induced for dual-type development. In other examples, the degree of polymerization of the exposed portion 10a is changed, such as depolymerization in a positive photoresist (or cross-linking in a negative photoresist).

As in some embodiments shown in Figures 8 and 9C, step 108 of the method 100 is followed by developing the photoresist in a developer. The development process forms a patterned photoresist 10'. In some embodiments, the polarity of the photoresist 10 after step 106 is changed, and a dual-type development process can be implemented. In some examples, the photoresist 10 is converted from a non-polar state (hydrophobic state) to a polar state (hydrophilic state), and then the exposed portion 10a can be removed by an aqueous solvent such as tetramethylammonium hydroxide (positive imaging), or can be An organic solvent such as butyl acetate removes the unexposed portion 10b (negative imaging). In some other examples, the photoresist 10 is converted from a polar state to a non-polar state, and then the exposed portion 10a can be removed by an organic solvent (positive imaging), or the unexposed portion 10b can be removed by an aqueous solvent (negative imaging) .

In this example shown in FIG. 9C, the unexposed portion 10b is removed during the development process. In this example shown in FIG. 9C, the patterned photoresist 10' has two circuit patterns. Then the following can also be used for the photoresist pattern of the trench.

As shown in Figures 8 and 9D, step 110 of the method 100 uses the patterned photoresist 10' as a mask to process the semiconductor structure 200, so the process is only applied to the semiconductor in the opening of the patterned photoresist 10' The structure 200, and the patterned photoresist 10' covers other parts of the semiconductor structure 200 so as not to be affected by the manufacturing process. In some embodiments, the process includes an etching process applied to the underlying layer 204, which uses the patterned photoresist 10' as an etching mask to transfer the pattern of the patterned photoresist 10' to the underlying layer 204. In other embodiments, the process includes an ion implantation process applied to the semiconductor structure 200, which uses a patterned photoresist 10' as an implant mask to form a variety of doped structures in the semiconductor structure 200.

In this example, the lower layer 204 is a hard mask layer. In this embodiment, the pattern is first transferred from the patterned photoresist 10' to the underlying layer 204, and then the pattern is transferred to other layers of the substrate 202. For example, dry (plasma) etching, wet etching, and/or other etching methods may be used to etch the underlying layer 204 through the openings of the patterned photoresist 10'. For example, the dry etching process may use oxygen-containing gas, fluorine-containing gas, chlorine-containing gas, bromine-containing gas, iodine-containing gas, other suitable gas and/or plasma, and/or a combination of the foregoing. Part or all of the patterned photoresist 10' may be consumed when etching the underlying layer 204. In one embodiment, any remaining patterned photoresist 10' can be stripped off to keep the patterned hard mask 204' on the substrate 202, as shown in FIG. 9E.

Although not shown in Figure 8, the method 100 may include other steps before, during, or after the above steps. In one embodiment, the substrate 202 is a semiconductor substrate, and the method 100 is performed to form a fin-shaped field effect transistor structure. In this embodiment, the method 100 includes forming a plurality of active fins in the semiconductor substrate 202. In this embodiment, step 110 further includes etching the substrate 202 through the opening of the patterned hard mask 204' to form a trench in the substrate 202; filling the trench with a dielectric material; and performing a chemical mechanical polishing process to form a shallow Trench structure; and epitaxial growth or recessed shallow trench isolation structure to form a fin-shaped active area. In another embodiment, the method 100 includes other steps to form a plurality of gates in the semiconductor substrate 202. The method 100 may also include forming gate spacers, doped source/drain regions, contacts for gate/source/drain structures, and the like. In another embodiment, a target pattern such as a metal circuit can be formed in a multilayer interconnection structure. For example, metal lines may be formed in the interlayer dielectric layer of the substrate 202, and the interlayer dielectric layer may be etched in step 110 to form a plurality of trenches. In the method 100, a conductive material such as a metal is filled into the trench, and the conductive material is polished by a process such as chemical mechanical polishing to expose the patterned interlayer dielectric layer, that is, a metal circuit is formed in the interlayer dielectric layer. According to the methods and materials of various embodiments of the present invention, the above non-limiting examples of devices/structures can be formed and/or improved.

The photoresist material provided by the embodiment of the present invention has a gradual composition to compensate for the problem of the base angle profile. In various embodiments, the photoresist material includes a polymer, a photoacid generator, a quencher, and a chemical additive mixed in a solvent, and its composition is designed to achieve an inconsistent distribution and corresponding inconsistent characteristic parameters (such as dissolution rate, photosensitivity, etc.). Sensitivity, etching resistance, or a combination of the above), therefore, it can compensate for the photoresist variation in the exposure process, reduce the base angle problem and improve the inconsistent critical dimensions of the patterned photoresist layer. The chemical additive can be a second polymer, a second photoacid generator, a second quenching agent, or a combination of the above. For example, the chemical additives include a second photoacid generator and a second quencher to increase the mutual compensation effect. In another example, the chemical additive includes a second photoacid generator and a second polymer.

The above-mentioned advanced lithography processes, methods, and materials can be used in a variety of applications, such as fin-shaped field effect transistors. For example, fins can be patterned to make the space between structures smaller, which is suitable for the above. In addition, spacers can be used to form fins of fin-shaped field effect transistors, and the spacers are also called cores. The spacer can be formed according to the above.

Therefore, an embodiment of the present invention provides a method of lithographic patterning. The method includes: coating a photoresist layer on a substrate, where the photoresist layer includes a first polymer, a first photoacid generator, and chemical additives mixed in a solvent; performing an exposure process on the photoresist layer; and applying the photoresist layer A development process is performed to form a patterned photoresist layer. The distribution of chemical additives in the photoresist layer is inconsistent.

In one embodiment, the chemical additive contained in the above method has a chemical structure with a first functional unit and a second functional unit that are chemically bonded together, wherein the first functional unit is designed so that the chemical additive is from the upper surface to the lower surface of the photoresist layer With gradual density, the second functional unit is designed to have characteristic parameters to compensate for the variation from the top surface to the bottom surface of the photoresist caused by the exposure process.

In one embodiment, the chemical additive in the photoresist layer of the above method is a dissolved additive with a molecular weight greater than 4000, wherein the surface tension of the first functional unit is less than 20mN/m, so that the gradual concentration of the dissolved additive decreases from the upper surface to the lower surface .

In one embodiment, the first functional unit of the above method includes fluorine.

In one embodiment, the second functional unit of the above method includes a hydrophobic unit, which is an alkyl group, a cycloalkyl group, or an adamantyl group, wherein the hydrophobic unit reduces the dissolution rate of the photoresist layer during the development process.

，其中X與Y為整數。 In one embodiment, the chemical structure of the dissolving additive in the above method is

, Where X and Y are integers.

In one embodiment, the above method further includes forming a carbon-rich underlayer on the substrate before coating the photoresist on the substrate, and forming a silicon-rich intermediate layer on the carbon-rich underlayer.

In one embodiment, the chemical additive of the above method is a second photoacid generator, wherein the chemical composition of the second photoacid generator in the exposure process is different from that of the first photoacid generator, and the chemical composition of the second photoacid generator is The first functional unit includes a polar unit to increase the force between the second photoacid generator and the silicon-rich intermediate layer, so that the gradual concentration of the second photoacid generator increases from the upper surface to the lower surface.

In one embodiment, the first photoacid generator in the above method has a uniform distribution in the photoresist layer.

，且第二光酸產生劑具有兩個鍵結 在一起的化學單元：

。 In one embodiment, the chemical structure of the first photoacid generator in the above method has two chemical units bonded together:

, And the second photoacid generator has two chemical units bonded together:

.

In one embodiment, the photoresist layer of the above method further includes a first quenching agent, and the first quenching agent has a uniform distribution in the photoresist layer; the chemical additive is the second quenching agent, and the first quenching agent The chemical composition of the second quencher is different from that of the second quencher; and the first functional unit in the second quencher contains a fluorine-rich polymer composition, so that the gradual concentration of the second quencher increases from the lower surface to the upper surface.

，且第二淬息劑包含的化學結構具有鍵 結在一起的兩個化學單元：

。 In one embodiment, the chemical structure contained in the first quenching agent of the above method has two chemical units bonded together:

, And the chemical structure of the second quenching agent has two chemical units bonded together:

.

In one embodiment, the chemical additive in the above method is a second polymer, and the composition of the first polymer and the second polymer are different; and in the photoresist layer before the exposure process, the second polymer and the first polymer Phase separation.

In one embodiment, in the above method, the first gradient concentration of the first polymer increases from the upper surface of the photoresist layer toward the lower surface; and the second gradient concentration of the second polymer increases from the upper surface of the photoresist layer toward the lower surface reduce.

In one embodiment, the first polymer in the above method has a first molecular weight, the second polymer has a second molecular weight, and the second molecular weight is greater than the first molecular weight, wherein the first molecular weight is between 2000 and 8000, and the first molecular weight is between 2000 and 8000. The molecular weight is between 6000 and 20000.

In one embodiment, the proportion of polar units in the chemical structure of the second polymer of the above method is greater than the proportion of polar units in the chemical structure of the first polymer.

，其中第二聚合 物的化學結構為

。 In one embodiment, the solubility of the second polymer in the development process of the above method is less than the solubility of the first polymer in the development process, wherein the chemical structure of the first polymer is

, Where the chemical structure of the second polymer is

.

。 In one embodiment, the etching resistance of the second polymer in the etching process of the above method is greater than the etching resistance of the first polymer in the etching process, wherein the chemical structure of the second polymer is

.

Another embodiment of the present invention provides a method of lithographic patterning. The method includes forming a photoresist layer on a substrate, wherein the photoresist layer includes a polymer, a first photoacid generator, and a second photoacid generator mixed in a solvent. The composition of the second photoacid generator is different from that of the first photoacid generator. The gradual concentration of the second photoacid generator decreases from the upper surface to the lower surface of the photoresist layer; the method further includes exposing the photoresist layer; and developing the photoresist layer to form a patterned photoresist layer.

，其中第二光酸產生劑包含的化學結構 具有鍵結在一起的兩個化學單元：

。 In one embodiment, the chemical structure contained in the first photoacid generator of the above method has two chemical units bonded together:

, Where the chemical structure of the second photoacid generator has two chemical units bonded together:

.

Another embodiment of the present invention also provides a method of lithographic patterning. The method includes forming a photoresist layer on the substrate. The photoresist layer includes a polymer, a photoacid generator, a first quenching agent, and a second quenching agent mixed in a solvent. The composition of the second quenching agent is different from that of the first quenching agent. The force between the second quenching agent and the polymer is greater than the force between the first quenching agent and the polymer. Therefore, the second quenching agent has a higher concentration at the bottom of the photoresist layer and has a higher concentration on the top of the photoresist layer. Lower concentration. The above method further includes performing an exposure process on the photoresist layer, and developing the photoresist layer to form a patterned photoresist layer.

The features of the above-mentioned embodiments facilitate the understanding of the present invention by those skilled in the art. Those skilled in the art should understand that the present invention can be used as a basis to design and change other manufacturing processes and structures to achieve the same purpose and/or the same advantages of the above-mentioned embodiments. Those with ordinary knowledge in the technical field should also understand that these equivalent substitutions do not depart from the spirit and scope of the present invention, and can be changed, substituted, or modified without departing from the spirit and scope of the present invention.

100‧‧‧Method

102, 104, 106, 108, 110‧‧‧ steps

Claims (10)

A method of lithography patterning includes: providing a photoresist solution, wherein the photoresist solution includes a first polymer, a second polymer, a first photoacid generator, and a photoresist A second photoacid generator with different composition is mixed in a solvent, wherein the chemical formula of the first polymer is:

And the chemical formula of the second polymer is:

X, Y, and Z are positive integers; wherein, the first photoacid generator includes the following two chemical units bonded together:

; And wherein the second photoacid generator has the following two chemical units bonded together:

The photoresist solution is coated on a substrate to form a photoresist layer. The photoresist layer has an upper surface away from the substrate and a lower surface facing the substrate. The application of the photoresist solution makes the first The photoacid generator has a uniform distribution from the upper surface to the lower surface of the photoresist layer, and the second photoacid generator has a gradually increasing concentration from the upper surface to the lower surface of the photoresist layer; An exposure process is performed on the photoresist layer; and a development process is performed on the photoresist layer to form a patterned photoresist layer. According to the method of lithographic patterning described in claim 1, wherein the second polymer has a gradually decreasing concentration from the upper surface to the lower surface of the photoresist layer. The method of lithography patterning as described in the scope of the patent application, wherein the first polymer has a gradually increasing first gradient concentration from the upper surface to the lower surface of the photoresist layer; and the second polymerization The substance has a second gradual concentration that gradually decreases from the upper surface to the lower surface of the photoresist layer. The method of lithography patterning as described in item 3 of the scope of the patent application, wherein the second molecular weight of the second polymer is greater than the first molecular weight of the first polymer. A method for lithographic patterning includes forming a photoresist layer on a substrate, wherein the photoresist layer has an upper surface away from the substrate and a lower surface facing the substrate, the photoresist layer includes a polymer, A first photo-acid generator and a second photo-acid generator are mixed in a solvent, wherein the second photo-acid generator and the first photo-acid generator have different compositions, and the first photo-acid generator There is a uniform distribution from the upper surface to the lower surface of the photoresist layer, the gradual concentration of the second photoacid generator increases from the upper surface to the lower surface of the photoresist layer, and the first photoacid generates The agent includes the following two chemical units bonded together:

The second photoacid generator has the following two chemical units bonded together:

Performing an exposure process on the photoresist layer; and developing the photoresist layer to form a patterned photoresist layer. According to the method of lithography patterning described in item 5 of the scope of the patent application, the photoresist layer further includes another polymer that is different in composition from the polymer. The method of lithography patterning as described in item 5 of the scope of the patent application further includes forming a carbon-rich underlayer on the substrate before coating the photoresist layer on the substrate; and forming a silicon-rich intermediate layer on the substrate. On the carbon-rich bottom layer. A method for lithographic patterning includes forming a photoresist layer on a substrate, the photoresist layer having an upper surface away from the substrate and a lower surface facing the substrate, wherein the photoresist layer includes a polymer , A first photoacid generator, a second photoacid generator, a first quenching agent, and a second quenching agent are mixed in a solvent, wherein the second photoacid generator and the first photoacid generator The composition of the acid generator is different, and the first photoacid generator has a uniform distribution from the upper surface to the lower surface of the photoresist layer, and the gradual concentration of the second photoacid generator is from the photoresist layer. The upper surface increases toward the lower surface, and the first photoacid generator includes the following two chemical units bonded together:

The second photoacid generator has the following two chemical units bonded together:

The composition of the second quenching agent is different from that of the first quenching agent, and the force between the second quenching agent and the polymer is greater than the force between the first quenching agent and the polymer, so that the The second quenching agent has a higher concentration at the bottom of the photoresist layer and a lower concentration at the top of the photoresist layer, and the first quenching agent includes the following two chemical units bonded together:

The second quenching agent includes the following two chemical units bonded together:

An exposure process is performed on the photoresist layer, and the photoresist layer is developed to form a patterned photoresist layer. According to the method of lithography patterning described in item 8 of the scope of patent application, the gradual concentration of the second quenching agent increases from the lower surface to the upper surface of the photoresist layer. According to the method of lithography patterning described in item 8 of the scope of patent application, the first quenching agent in the photoresist layer has a uniform distribution.

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